Spraying gun



United States Patent O SPRAYING GUN (Iscar Froidevaux, Antony, France,assigner to Socit dite: Tecalemit, Societe Anonyme, Paris, FranceApplication November 28, 1952, Serial No. 323,080

.Claims priority, application France December 19, 1951 2 Claims. (Cl.299-86) My invention relates to a spraying gun which is absolutelyfool-proof fory the reason that no parts are included in itsconstruction which are liable to suffer from careless handling of thegun and which is particularly suitable for spraying such viscous andsticky materials as mastics or bitumens for the purpose e. g. ofsilencing parts liable to vibrate.

With this end in view, my spraying gun is only composed of the fewfollowing parts:'a barrel which provides a reservoir for a charge of thematerial to be sprayed; a hollow tie rod which extends axially throughsaid barrel and which is formed at either end thereof with an externalscrewthread; a handle formed with a side boss and bored with a thoroughlongitudinal channel communicating at its one end with a line for thesupply of a compressed fiuid, at intermediate points with cross channelsleading through said boss respectively to the channel in said hollowcross tie and into the reservoir in said barrel and at its opposite endwith a vent; a head formed with a rim providing a socket for the outerend of said barrel, tapped with a hole for the reception of the outerend of said hollow tie rod and with two further holes in which a fillingnipple and the spraying device proper are screwed respectively and anidle piston slidably fitted both in said barrel and on said L said chokeis a hole in which a vent plug is received the bore of which is largerthan that of the choke, the combination of the choke with the ventproviding an ejector in which the former acts as the jet and the latteras the nozzle. The said ejector does not partake of the spraying actionproper, its only purpose being to assist the release of the pressureapplied formerly to the rear side of the idle piston and even to createa slight vacuum as soon as the supply of pressure fiuid is cut ofi.

Further advantages and features of my invention will be evidenced in thefollowing specification, reference being had to the appended drawing inwhich a spraying gun according to my invention is illustrated inlongitudinal sectional view.

In the drawing, 1 designates the gun barrel, which provides a reservoirfor the material to be sprayed, 2 the side boss solid with the gunhandle 3 while 4 designates the head which carries the filling nippleand the spraying device proper. I v

The parts 1, 2 and 4 are tied together by means of an axial hollow rod 5which has screwthreaded ends en gaged in holes tapped in the boss andthe head respectively; joint rings 6, 7 are interposed between eitherend of the barrel 1 and the boss 2 and the head 4 respectively.

Before the set of parts are assembled an idle piston 8 is made a slidingfit in the barrel 1 and on the hollow tie rod 5. f

Bored in handle 3 is a channel 9 which through a cross channel 10communicates with the channel 11 in the tie rod 5. Beyond thecrosschannel 10 the axial channel 9 is formed with a choke 12-whichcommunicates through a further cross `channel 13'with the reservoir inbarrel 1.

Beyond said cross channel 13 said channel 9 andI choke 12 extend in avent channel 14. t l l y l Channels 12 and 14 are so arranged relativeto each other and to cross channel 13 as toperform the function of anejector in which 12 acts as the jet and 14 as the nozzle. l

The purpose of such an ejector 12-14 is. to prevent any pressure beingexerted upon the idle piston as long as no material is to be sprayed andto ensure a quick release of the pressure in the reservoir as soon asthe spraying process ceases.

Tapped through head 4 are a hole 15 for the reception of a fillingnipple 17 and a hole 16 for the reception of a delivery nozzle 1S with ataper end 19.

The head 4 is formed with a nipple 20 which is screwthreaded at 21 forthe connection of a screw cap 22 delimited inside by a conical surface23 corresponding to the taper of the delivery nozzle 18.

Practically, the cap 22 is so dimensioned that when screwed home on thethreaded portion of nipple 20 the annular slit between the inside of 22and the outside of 23 a sufficient stream of the fiuid=under pressure`is allowed to rush therethrough to ensure perfect atomization of thematerial in the reservoir. Nevertheless, it is always possible toincrease the sectional area of the slit by unscrewing the cap 22 to alimited extent.

The channel 11 in tie rod 5 communicates through a port with an annularchamber 24 surrounding the nozzle 18 in the bore in nipple 20, fromwhich chamber 24 the pressure fiuid is deflected by fillets 18a milledin the skirt of nozzle 18 towards the annular slit delimited by theconical surfaces 19 and 23.

The nipple 17 is designed to allow the reservoir 1 being refilled fromthe conventional pump pail and can be closed with the aid of a screwplug 25 provided with a knurled head and with a tail piece 26 of specialdesign to serve for the purpose explained as follows:

The bore in the nozzle 18 is formed with a restricted outlet 2'7 for thereception, before the filling of the reservoir is started, of said tailportion 26 of screw plug 25.

My spraying gun operates as follows:

For the filling of the reservoir 1 the screw plug 25 is taken away andfitted with its tail portion 26 into the orifice 27 of nozzle 18,whereby the gun is closed at its delivery end and the reservoir 1 can berefilled.

ln proportion as material is forced into it the idle piston 8 therein isdriven backwards until it is stopped by the boss 2 in which the barrel 1is socketed, when the reservoir is full.

Thereafter, the plug 25 is pulled out of the nozzle 18 and screwed againinto the filling nipple 17.

ln spraying out the material in reservoir 1 the pressure fluid isswitched into the channel 9 in the handle 3. With the orifice of ejector12e-14 open the working uid cannot act upon the idle piston 8 since itis allowed to escape to the outside on the one hand through crosschannel 10, axial channel 11, chamber 24 and the annular slit between 19and 23 and on the other hand through ejector 12-14 while creating aslight vacuum on the back side of the idle piston 8.

It is only necessary for the operator to close the vent 14 with histhumb to set the ejector out of action, as a result of which the uidpressure is caused to act upon the back side of the idle piston 8 andthereby to force the materialin the reservoir through the nozzle 27.

The worm of material thus forced out is caught by the jet of pressurefluid expelled through the slit between the conical surfaces 19, 23 (seeangle a) and is pro jected thereby as a conical spray (see angle It willbe understood easily that given the pressure of the ejecting fluid it ispossible to control the amount of material ejected simply by more orless uncovering the-vent 14.

The outilow of material is stopped altogether as soon as the vent 14 iscompletely uncovered since the ejector 12-14 will immediately becomeonce more effective to release the pressure prevailing in the reservoir1 and furthermore to create a slight vacuum within the same.

It will be appreciated that the gun can successfully be used forspraying other materials, e. g. cement wash or like coating materials tobe sprayed onto walls or similar surfaces.

' What I claim is:

l. A spraying gun for the application of viscous mathrough said boss tothe channel in said hollow cross tie and a second cross channelcommunicating with said longitudinal channel and leading into thereservoir in said barrel, and said longitudinal channel being formed atits opposite end with a vent with an opening closable by the linger ofthe operator of the gun, a head formed '-1- with a rim providing asocket for the outer end of said barrel, said head being tapped with ahole for the reception of the outer end of said hollow tie rod and withtwo additional holes, a lling nipple received in one of said holes, aspraying unit received in the other of said holes, and an idle pistonslidably fitted in said barrel and on said hollow tie rod.

2. A spraying gun for the application of viscous materials whichcomprises a barrel which provides a reservoir for a charge of thematerial to be sprayed, a hollow tie rod extending axially through saidbarrel and formed at each end with an external screwthread, a handlemember formed with a side boss receiving one end of said tie rod andbored with a through longitudinal channel communicating at one end witha line for the supply of a compressed fluid, a cross channelcommunicating with said longitudinal channel and leading through saidboss to the channel in said hollow cross tie and a second cross channelcommunicating with said longitudinal channel and leading into thereservoir in said barrel, and said longitudinal channel being formed atits opposite end with a vent with an opening closable by the finger ofthe operator of the gun, said longi-l tudinal channel being chokedopposite the vent, a head formed with a rim providing av socket for theouter end of said barrel, said head being tapped with a hole for thereception of the outer end of said hollow tie rod and with twoadditional holes, a filling nipple closed by a screw plug received inone of said holes, a spraying unit received in the other of said holes,said spraying unit including a cone-tipped nozzle for the discharge ofthe materiali enclosed in the barrel, a cone-tipped cap drilled throughits apex with an outlet and delimiting an annular chamber surroundingthe conical tip of the nozzle and communicating through the head withthe channel in the hollow tie rod, and an idle piston slidably fitted insaid barrel and on said hollow tie rod.

References Cited in the iile of this patent UNITED STATES PATENTS716,910 Lubbecke Dec. 30, 1902 l1,090,119 Overbeke June 18, 19121,578,944 Wilkinson Mar. 30, 1926 1,590,430 Erby lune 29, 1926

